When logins are saved into the couchdb database, they need an _id to uniquely identify themselves. It is possible to let couchdb generate the _id value. However using couchdb-generated _id values means that we need to perform existance checks client-side before saving a login to ensure uniqueness

There should only every be a single record for a given login in the database. Couchdb internally requires that each document have a unique _id value. If the _id for a login is generated manually we can ensure each login only gets saved once.